Index-Based Iterative Source-Channel Decoding

• Main Authors: Yen-Chang Pan, 潘彥璋
• Other Authors: Wen-Whei Chang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/88257684317015651263

碩士 === 國立交通大學 === 電信工程系所 === 96 === This thesis presents a new method of iterative source-channel decoding (ISCD) technique. The ISCD consists of a channel decoder followed by a source decoder, which are connected with a feedback loop. The main attraction of ISCD is that reliability gains resulting from both artificial and source residual redundancy can be exchanged iteratively in a turbo-like process. The extrinsic information produced by each decoding algorithm is used to strengthen the a priori information of another decoder. However, conventional ISCD system computes the extrinsic information in bit-level and therefore the correlation of source parameters cannot be fully utilized. A new index-based ISCD is presented which consists of a softbit source decoder (SBSD) and a channel decoder based on the modified BCJR algorithm using sectionalized code-trellis. The index-based ISCD does not produce bit-level information in its decoding process and therefore improves the way of utilizing the source correlation. Simulation results show that significant improvements of error robustness are achieved by ISCD compared to conventional concatenated decoding schemes. Furthermore, the index-based ISCD outperforms the bit-based ISCD under all channel-SNR conditions.